I hated the Cover Fx drops cause it was grey as hell, this stuff I am ab-so-freaking-lutely in love with. For one this is very golden and it doesn’t loose that upon being mixed into anything else. Second, the pigmentation is off the charts. One drop in moisturiser is sufficient to create a pretty decently pigmented tinted moisturiser. Two drops is medium coverage. Third, and probably the most important detail, it doesn’t affect the finish of anything that you add it to. The CF always changed the texture and finish of my foundations, and not in a good way. I believe the BIY drops are water based, the very liquid consistency leads me to believe that and I think that’s the reason it doesn’t affect the finish.
One of my big issues with the CF was that the darkest shade in the golden range was still not quite dark enough, because of that it consistently lightened every foundation that I added it to, instead of adjusting the undertone which is kind of what it was created to do. The BIY drops don’t do that. I’ve been adding it to a couple new foundations that I’ve gotten where the shade is right, but the undertone could use a little more gold in it. All this does is make the undertone better for me without changing anything other than that. In the pictures I have it mixed with the Clinique Moisture Surge. The first photo is just one drop, and the second is two drops.
I do have two problems with this though, first it's $33 and you only get .34oz. Second, I use 155, the second to last shade, and I'm a medium brown, so not that dark. All in although, I love this thing.